This invention relates to devices which operate with needles to transfer fluids to or from a prosthesis and more particularly to a septum with a novel needle stop arrangement that prevents a needle from penetrating a fluid transfer structure after the needle has accessed a fluid chamber of the septum.
As used herein the term "fluid transfer structure" relates to external fluid flow structure communicating with the fluid chamber of a septum.
Prosthetic devices implanted in the body to restore shapes and contours that have been surgically altered or accidentally deformed usually require infusions of fluid to restore proper pocket tension or to modify the shape or contour of the prosthesis. However it is normally not feasible to make direct access with a prosthesis for fluid infusions or fluid withdrawals due to the remote location of many prostheses and due to possible leakage problems that may develop if a prosthesis is penetrated by a needle.
Septums have thus become a well known vehicle for transferring fluid to a prosthesis through a fluid transfer structure and alternatively can be used to drain unwanted fluids from certain areas of the body. A septum, which is generally implanted near a prosthesis, usually includes a fluid chamber sealed by a needle penetrable seal member. Fluid is infused into or withdrawn from the fluid chamber by a hypodermic needle that accesses the fluid chamber through the needle penetrable seal member. The fluid transfer structure normally communicates with the fluid chamber and interconnects with the prosthesis.
Once a needle has penetrated the fluid chamber of a septum it is necessary to stop further movement of the needle in the septum to prevent the needle from passing completely out of the fluid chamber. It is thus well known to provide a needle stop member in a septum, usually at the base of the fluid chamber. The needle stop member is generally constructed of a needle impermeable material to prevent further movement of a needle out of the fluid chamber.
The fluid transfer structure which extends from the fluid chamber is usually formed of a relatively soft flexible material that does not resist penetration by a needle. Since the septum is normally implanted below the skin it is difficult to predetermine the path of the needle which accesses the fluid chamber. Thus the area of the septum where the fluid transfer structure joins the fluid chamber is vulnerable to penetrations by a needle if such needle is inadvertently oriented in a direction toward the fluid transfer structure during a fluid infusion or fluid withdrawal operation.
If a needle penetrates the fluid transfer structure after accessing the fluid chamber, the fluid transfer operation cannot be completed. Furthermore it may be difficult to detect when a needle has penetrated or passed through the fluid transfer structure, since such structure is implanted below the surface of the skin. Under these circumstances the person administering a fluid transfer operation is often not aware that fluid may be bypassing the fluid chamber.
It is thus desirable to provide a septum having a needle stop structure that prevents a needle in a fluid chamber from penetrating the fluid transfer structure and does not obstruct the flow of fluid into the fluid transfer structure.